docs: def is_private_addr(x):
      """Returns True if the IPv4 Address is an RFC 1918 private address."""
      paddrs = ['10.0.0.0/8', '172.16.0.0/12', '192.168.0.0/16']
      found = False
      for ipr in paddrs:
          try:
              if ipaddress.ip_address(x) in ipaddress.ip_network(ipr):
                  found = True
                  continue
          except:
              break
      return found